How to Estimate Your One Rep Max (Without Testing It)

Testing your true one-rep max is risky, exhausting, and requires a spotter. The good news: if you can lift a weight for 2–10 reps, math can estimate your max with surprising accuracy.

The formulas

Three widely used equations — all take the weight lifted and reps completed:

Epley (most popular):
  1RM = Weight × (1 + Reps/30)

Brzycki:
  1RM = Weight × 36 / (37 − Reps)

Lombardi:
  1RM = Weight × Reps^0.10

These formulas are most accurate between 2–10 reps. Above 10, estimates become less reliable because muscular endurance starts dominating over pure strength.

Worked example

You bench press 80 kg for 6 reps with good form (couldn’t do a 7th):

Epley:    80 × (1 + 6/30) = 80 × 1.2 = 96 kg
Brzycki:  80 × 36/(37−6) = 80 × 36/31 = 92.9 kg
Lombardi: 80 × 6^0.10 = 80 × 1.196 = 95.7 kg

Average estimated 1RM ≈ 95 kg

Using your 1RM for training

Once you know your estimated max, program percentages:

Percentage	Reps	Training effect
90–100%	1–2	Max strength / peaking
80–90%	3–5	Strength
70–80%	6–8	Hypertrophy (muscle growth)
60–70%	8–12	Hypertrophy / endurance
50–60%	12–15+	Muscular endurance

Example: if your 1RM squat is 120 kg, a hypertrophy set uses 84–96 kg for 6–8 reps.

When to use estimated 1RM

• Starting a percentage-based strength program (5/3/1, Texas Method, etc.)
• Tracking progress without maxing out (test every 4–6 weeks with sub-maximal sets)
• Comparing strength across lifts (relative strength ratios)
• Setting competition attempt weights (powerlifting prep)
• Returning from injury — establish baselines safely

Tips for accurate estimates

• Use a weight you can do for 3–6 reps — this is the sweet spot for accuracy
• The set must be to true failure (or 1 rep from failure)
• Rest 3–5 minutes before the test set for full recovery
• Don’t estimate from machine exercises — free weight only
• Retest every 4–8 weeks as strength changes
• Upper body formulas tend to overestimate slightly; lower body is more accurate

Estimate all your lifts instantly with OurDailyCalc’s one rep max calculator — enter your weight and reps for Epley, Brzycki, and Lombardi estimates side by side.

TL;DR

• 1RM = Weight × (1 + Reps/30) is the most common formula (Epley)
• Best accuracy with 2–10 rep sets taken to near-failure
• Use percentages of 1RM to program training intensity
• Retest every 4–8 weeks without actually maxing out
• Safer, less fatiguing, and surprisingly accurate vs. true max attempts